The investigation covers a total of 170,000 2005 through 2007 model year Freestyles and, so far, NHTSA has linked 18 crashes to the lunging. No injuries have been attributed to the abnormal vehicle behavior, however.

NHTSA says that the Freestyles in question have lunged forward even though drivers don't have their feet on the gas pedal. A hit of the brakes will stop the lunging Freestyle, however.

Some complaints also cited having the steering wheel turned hard left or right, as well as an apparent increased occurrence if operating the vehicle's air conditioning system. The lunge reportedly occurs at low speeds only and has taken place in vehicles placed in both reverse and forward gears.

The investigation covers the Freestyle, but not the refreshed Ford Taurus X that replaced the weak-selling Freestyle in 2008. The Taurus X featured an uprated 3.5-liter V6 rather than the Freestyle's 3.0-liter V6, a powertrain change that could have cured the lunging issue.

NHTSA and the buying public have a heightened sense of concern with unintended acceleration after Toyota was forced to recall the bulk of its lineup over the last few years. This Freestyle investigation differs in that vehicles appear to only accelerate unintentionally at low speeds and because an application of the brakes will stop vehicles.